The present invention is directed to a lubricating system and, more particularly, is directed to a lubricating system which also provides for cooling of an electric drive motor within a vacuum environment for an ultracentrifuge.
Most lubricating systems for drives of ultracentrifuges are maintained outside of the vacuum environment which is found in the rotor chamber of the centrifuge. Most of these lubricating systems use oil and are regulated by orifices or valves that can become plugged or damaged. In many instances the amount of oil which is introduced to the spindle or drive shaft is variable according to how fast the shaft is rotating. When the spindle is at high speed, a high oil flow may be too great and more than necessary, causing operating problems to the centrifuge. On the other hand, at low spindle speeds not a sufficient amount of oil being supplied for the necessary lubrication during rotation.
When an electric motor such as an induction motor is utilized for high speed rotation, it is necessary to provide some type of cooling to the armature of the motor. However, if the motor is to be placed in a vacuum environment for operation such as explained in my copending patent application entitled A Direct Drive High Speed Ultracentrifuge, it is necessary to provide some type of cooling to the motor. In other non-vacuum operations some type of fan or circulation means is utilized to promote the flow of cooling air. However, in a vacuum it is not possible to circulate air to transfer the heat generated during the operation of the motor. Therefore, the utilization of an electric motor in a vacuum environment poses a unique problem with respect to providing the requisite cooling functions for the motor during its high speed operation.
It is also desirable, when a drive system is operating in a vacuum environment, that external lubricating lines not be used because their interface would represent potential adverse effects on the vacuum environment. Also these lines present possible leakage points in the lubricating system.